1. Field of the Invention
The present invention relates to an expander roll used to smooth out wrinkles in a sheet-like material, such as paper, cloth, or film, or used to tenter the sheet-like material.
2. Description of the Prior Art
For example, an expander roll in which a rubber-made roll body that is made slightly shorter than a curved shaft is attached to the outer periphery of the shaft with bearings therebetween or an expander roll in which a plurality of stainless-steel-made cylindrical roll members are attached to the outer periphery of a curved shaft with bearings therebetween is known as an expander roll used in a paper-manufacturing process.
In the former expander roll employing the rubber-made roll body, the rubber-made roll body is badly worn down because of friction with a sheet of pulp generated by its high-speed rotation, and high paper-manufacturing accuracy is hardly obtainable. Therefore, there are demands to widely use an expander roll employing the latter stainless-steel-made roll member that does not have these drawbacks not only in a dry part of the paper-manufacturing process but also in a wet part including a wire part and a press part.
Conventionally, an expander roll shown, for example, in FIG. 8 (Japanese Examined Patent Application Publication No. Sho-57-51573) is known as an expander roll employing the stainless-steel-made cylindrical roll member. In this expander roll, a plurality of roll elements 43 are successively attached to the outer periphery of a curved shaft 41 with a bearing 42, and the adjoining roll elements 43 are connected together through a connector 44, a buffer body 45, and a clutch pin 46. An O ring 48 fitted into a groove 47 formed in the outer periphery of the connector 44 prevents grease of the bearing 42 from leaking out to the outer circumferential surface of the roll.
However, when the plurality of roll elements 43 attached to the curved shaft 41 rotates at high speed, the adjoining roll elements 43 slightly recede from each other at a side corresponding to a direction in which the shaft 41 is curved, whereas the adjoining roll elements 43 slightly approach each other at the opposite side in the direction in which the shaft 41 is curved. Therefore, each roll element 43 repeatedly makes a reciprocating movement in the lengthwise direction of the shaft 41 in response to its high-speed rotation, and, as a result, the O ring 48 formed in the outer periphery of the connector 44 is swiftly worn away, and its liquidtightness is easily lost in a short time. Therefore, conventional problems lie in the fact that the risk of allowing the grease of the bearing 42 to leak out to the outer surface of the roll element 43 occurs with the lapse of time during which the expander roll is used and in the fact that water is infiltrated into the roll element 43 so as to cause breakdown of the bearing 42 when the expander roll is used in the wet part of the paper-manufacturing process.
Likewise, an expander roll shown, for example, in FIG. 9 (U.S. Pat. No. 4,236,285) is known as an expander roll employing the stainless-steel-made cylindrical roll member. In this expander roll, a plurality of spools (cylindrical roll members) 53 are successively attached to the outer periphery of a curved shaft 51 with a bearing 52, and a seal ring 55 is provided at both ends of a connection member 54 facing a gap between the adjoining spools 53 so as to obtain liquidtightness.
However, also in this expander roll, each spool 53 repeatedly makes a slight reciprocating movement in the lengthwise direction of the shaft 51 in response to the high-speed rotation of each spool 53, and the seal ring 55 is easily worn away in a short time. Therefore, the same problem as in the expander roll employing the O ring 48 has arisen.
It is therefore an object of the present invention to provide an expander roll that has a structure, in which a plurality of metallic roll members, such as stainless-steel-made roll members, are attached to the outer periphery of a curved shaft, capable of reliably obtaining liquidtightness even when it is rotated at high speed.